Can Blender model interaction of complex shapes
You won't be able to accurately produce the interaction of Stone Tetra Pods with the beach area and water in Blender. I'd advise against using it as a tool for engeneering research. It is best used as a tool for visual representations which don't have to be physically accurate. (However, there have been plenty of other applications.)

However, Blender has the rigid body system which can be used to simulate rigid bodies.


Add a rigid body world.
Add the objects (related) and make them active rigid bodies (with correct friction values e.g.).
Cache the simulation.


In this example the resulting interlocking of the shapes can be seen.